- Scientists have invented a plastic solar cell that can
turn the sun's power into electrical energy, even on a cloudy day.
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- The plastic material uses nanotechnology and contains
the first solar cells able to harness the sun's invisible, infrared rays.
The breakthrough has led theorists to predict that plastic solar cells
could one day become five times more efficient than current solar cell
technology.
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- Like paint, the composite can be sprayed onto other materials
and used as portable electricity. A sweater coated in the material could
power a cell phone or other wireless devices. A hydrogen-powered car painted
with the film could potentially convert enough energy into electricity
to continually recharge the car's battery.
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- The researchers envision that one day "solar farms"
consisting of the plastic material could be rolled across deserts to generate
enough clean energy to supply the entire planet's power needs.
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- "The sun that reaches the Earth's surface delivers
10,000 times more energy than we consume," said Ted Sargent, an electrical
and computer engineering professor at the University of Toronto. Sargent
is one of the inventors of the new plastic material.
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- "If we could cover 0.1 percent of the Earth's surface
with [very efficient] large-area solar cells," he said, "we could
in principle replace all of our energy habits with a source of power which
is clean and renewable."
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- Infrared Power
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- Plastic solar cells are not new. But existing materials
are only able to harness the sun's visible light. While half of the sun's
power lies in the visible spectrum, the other half lies in the infrared
spectrum.
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- The new material is the first plastic composite that
is able to harness the infrared portion.
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- "Everything that's warm gives off some heat. Even
people and animals give off heat," Sargent said. "So there actually
is some power remaining in the infrared [spectrum], even when it appears
to us to be dark outside."
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- The researchers combined specially designed nano particles
called quantum dots with a polymer to make the plastic that can detect
energy in the infrared.
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- With further advances, the new plastic "could allow
up to 30 percent of the sun's radiant energy to be harnessed, compared
to 6 percent in today's best plastic solar cells," said Peter Peumans,
a Stanford University electrical engineering professor, who studied the
work.
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- Electrical Sweaters
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- The new material could make technology truly wireless.
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- "We have this expectation that we don't have to
plug into a phone jack anymore to talk on the phone, but we're resigned
to the fact that we have to plug into an electrical outlet to recharge
the batteries," Sargent said. "That's only communications wireless,
not power wireless."
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- He said the plastic coating could be woven into a shirt
or sweater and used to charge an item like a cell phone.
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- "A sweater is already absorbing all sorts of light
both in the infrared and the visible," said Sargent. "Instead
of just turning that into heat, as it currently does, imagine if it were
to turn that into electricity."
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- Other possibilities include energy-saving plastic sheeting
that could be unfurled onto a rooftop to supply heating needs, or solar
cell window coating that could let in enough infrared light to power home
appliances.
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- Cost-Effectiveness
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- Ultimately, a large amount of the sun's energy could
be harnessed through "solar farms" and used to power all our
energy needs, the researchers predict.
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- "This could potentially displace other sources of
electrical production that produce greenhouse gases, such as coal,"
Sargent said.
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- In Japan, the world's largest solar-power market, the
government expects that 50 percent of residential power supply will come
from solar power by 2030, up from a fraction of a percent today.
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- The biggest hurdle facing solar power is cost-effectiveness.
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- At a current cost of 25 to 50 cents per kilowatt-hour,
solar power is significantly more expensive than conventional electrical
power for residences. Average U.S. residential power prices are less than
ten cents per kilowatt-hour, according to experts.
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- But that could change with the new material.
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- "Flexible, roller-processed solar cells have the
potential to turn the sun's power into a clean, green, convenient source
of energy," said John Wolfe, a nanotechnology venture capital investor
at Lux Capital in New York City."
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- http://news.nationalgeographic.com/
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